Many existing CFCs are known to be ozone-depleting compounds. Thus, the use of these compounds has been curtailed in favor of chemicals that are more commercially acceptable. In some cases, alternate CFC compounds have been found to be both effective and more environmentally friendly. As one example, 1-chloro-3,3,3-trifluoropropene (hereinafter “1233zd”) has been found to have a wide variety of uses, for example as a heat transfer agent, as a foaming agent, and as a solvent, among other uses. U.S. Patent Publication Nos. 2008/0098755, entitled “Heat Transfer Methods Using Heat Transfer Compositions Containing Trifluoromonochloropropene,” and 2008/0207788, entitled “Foaming Agents, Foamable Compositions, Foams and Articles Containing Fluorine Substituted Halogens, and Methods of Making the Same” and U.S. Pat. No. 6,362,383, entitled “Hydro-Fluorination of Chlorinated Hydrocarbons” all disclose examples of such uses. The contents of each of these references are incorporated herein by reference in their entirety.
1233zd may be produced by any one of a number of different methods. For example, U.S. Pat. No. 7,829,747, entitled “Process for Dehydrofluorination of 3-chloro-1,1,13-tetrafluoropropane to 1-chloro-3,3,3-trifluoropropene”; U.S. Pat. No. 5,710,352, entitled “Vapor Phase Process for Making 1,1,1,3,3-pentafluoropropane and 1-chloro-3,3,3-trifluoropropene;” U.S. Pat. No. 6,111,150, entitled “Method for Producing 1,1,1,3,3-pentafluoropropane;” and U.S. Pat. No. 6,844,475, entitled “Low Temperature Production of 1-chloro-3,3,3-trifluoropropene (HCFC-1233zd)” all describe several methods for making 1233zd. The contents of each of these references incorporated by reference herein in their entirety.
1233zd has two isomers, (E) and (Z), with different physical properties. As one example of the different properties between the two isomers, 1233zd(Z) has a boiling point of approximately 38° C., whereas 1233zd(E) has a boiling point of approximately 19° C. In some applications, it is desirable to use either pure 1233zd(E), pure 1233zd(Z), a particular blend of the (Z) and (E) isomers, or a particular blend of one or both of the 1233zd isomers and another compound in order to control the properties of the solution. For example, in some solvent applications, it is desirable to have a relatively high boiling point. In some such applications, pure 1233zd(Z) may have more desirable physical properties (e.g., a higher boiling point) than either pure 1233zd(E) or mixtures of the two 1233zd isomers.
In some prior art isomerization reactions, reagents (defined herein as any chemically reactive materials, i.e., not the 1233zd itself or the various catalysts described herein) are used to facilitate the isomerization of the 1233zd. For example, in one prior art isomerization reaction bromine is added to 1233zd(E) in order to isomerize 1233zd. In some embodiments of the present invention, the isomerization reaction is reagent-free, or it does not require the use of any reagents. As further described below, in some embodiments the absence of reagents facilitates the production of pure 1233zd, and more particularly may facilitate the production of pure 1233zd(Z) and pure 1233zd(E).
Isomerization of 1233zd(E) to form 1233zd(Z) is disclosed in the U.S. Pat. No. 8,217,208, the contents of which are incorporated herein by reference in its entirety, which provides a low temperature isomerization process. The deficiency of this process, however, is that it results in low selectivity to 1233zd(Z) and the formation of significant amounts of by-products (see, for example, table 3 of example 4 exhibiting selectivity to 1233zd(Z) of about 80%).
Accordingly, there exists a need for processes that selectively provide one or both of the commercially desirable isomers of 1233zd, particularly for the conversion of 1233zd(E) to form 1233zd(Z) with increased yield and selectivity.